quoin up

In letterpress printing, to quoin up meant to insert and tighten quoins, the metal wedges that held a forme of type rigid within the chase. A quoin (pronounced "coin") was a steel or brass wedge, usually L-shaped or rectangular, driven into the narrow gaps between the forme and the chase walls. The process required a quoin key, a T-shaped tool that fitted into notches on the quoin head, allowing the printer to apply leverage and drive the wedge home. Without proper quoining, type would shift during impression, causing blurred or misaligned print.

The procedure demanded skill and judgment. Too little pressure left the forme loose and unstable; too much could bend the type or crush it against the chase edge. A printer would quoin up along both horizontal and vertical axes, working methodically to ensure even pressure across the entire forme. The sequence mattered: quoins were typically tightened in a specific order to avoid trapping air or creating stress concentrations that might crack brittle type or damage woodcuts locked into the same chase.

Different quoin designs emerged over centuries of printing practice. Simple wedges required manual force; later, screw quoins allowed finer control through rotation. Some printers favored brass quoins for their non-magnetic properties when working near iron type; others preferred steel for durability. The quoin key itself came in various weights and handle styles, reflecting regional preference and the scale of the printing house. Large format work demanded heavier quoins and longer keys to generate sufficient clamping force.

Quoining up was routine work, repeated dozens of times daily in an active printing house, yet it was rarely documented in technical manuals. Apprentices learned the feel through repetition, developing an intuitive sense of when sufficient pressure had been applied. The term survives in printing history and antique equipment collections, but the practice vanished as offset lithography and digital printing displaced letterpress as the dominant technology in the mid-twentieth century.